Liquid based formulations of bacteriophages for the management of waterborne bacterial pathogens in water microcosms.

Water resources are contaminated by life-threatening multidrug resistant pathogenic bacteria. Unfortunately, these pathogenic bacteria do not respond to the traditional water purification methods. Therefore, there is a need of environmentally friendly strategies to overcome the problems associated with the antimicrobial resistant bacterial pathogens. In the present study, highly potent lytic phages against multidrug-resistant Salmonella enterica serovar Paratyphi B, Pseudomonas aeruginosa and Klebsiella pneumoniae were isolated from the Pavana river water. They belonged to the Podoviridae and Siphoviridae families. These phages were purified and enriched in the laboratory. Monovalent formulations of φSPB, BVPaP-3 and KPP phages were prepared in three different liquids viz., phage broth, saline and distilled water. The phages were stable for almost 8-10 months in the phage broth at 4 °C. The stability of the phages in saline and distilled water was 5-6 months at 4 °C. All of the phages were stable only for 4-6 months in the phage broth at 30 °C. The monovalent phage formulation of φSPB was applied at MOI < 1, as disinfectant against an exponential and stationary phase cells of Salmonella enterica serovar Paratyphi B in various water microcosms. The results indicated that there was almost 80 % reduction in the log phase cells of Salmonella serovar Paratyphi B in 24 h. In stationary phase cells, the reduction was comparatively less within same period. At the same time, there was concomitant increase in the phage population by 80% in all the microcosms indicating that φSPB phage is highly potent in killing pathogen in water. Results strongly support that the formulation of φSPB in the phage broth in monovalent form could be used as an effective biological disinfectant for preventing transmission of water- borne bacterial pathogens, including antimicrobial resistant ones.